The present invention relates to a locking device and, more particularly, to a locking device especially adapted for locking a door of an automobile.
In conventional motor-driven automobile door locking devices, a lock lever is disposed within the main body of a locking device and operatively coupled to a power source or a motor so that the lock lever is moved or rotated between an unlocking position in which the latching mechanism within the locking device can be released and a locking position in which the latching mechanism cannot be released. That is, the output of the motor is transmitted through a transmission mechanism, such as a mechanism including a pinion and a sector gear, to the lock lever. Such a driving mechanism of the type described above is incapable of producing a driving force beyond a certain limit so that when a greater driving force is needed, a motor with a higher output must be used.
In the conventional automobile door locking device, in order to hold the lock lever in the locking position or in the unlocking position, the so-called over-center spring is used which can bias the lock lever in either direction when the lock lever has passed past a dead center point. The over-center spring has a relatively strong force so that, in order to rotate the lock lever, a force which is greater than the force of the over-center spring must be applied to the lock lever. Therefore, there is a problem in that the power source or the motor must have a high output power.